20543 has 2 divisors, whose sum is σ = 20544. Its totient is φ = 20542.

The previous prime is 20533. The next prime is 20549. The reversal of 20543 is 34502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20543 - 2⁶ = 20479 is a prime.

It is an Ulam number.

It is equal to p₂₃₁₈ and since 20543 and 2318 have the same sum of digits, it is a Honaker prime.

It is a zygodrome in base 4.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10271 + 10272.

It is an arithmetic number, because the mean of its divisors is an integer number (10272).

2²⁰⁵⁴³ is an apocalyptic number.

20543 is a deficient number, since it is larger than the sum of its proper divisors (1).

20543 is an equidigital number, since it uses as much as digits as its factorization.

20543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 14.

The square root of 20543 is about 143.3282944851. The cubic root of 20543 is about 27.3876407222.

The spelling of 20543 in words is "twenty thousand, five hundred forty-three".